对 mysql Illegal mix of collations (gbk_chinese_ci,IMPLICIT)
即可，如：
jdbc:mysql://localhost:3306/ipanel?useUnicode=true&characterEncoding=UTF-8
hibernate和jdbc的参数设置是不一样，但大体相同，网上类似的资料很多。
最重要的是这个问题：
Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (gb2312_chinese_ci,IMPLICIT) for operation '='
相信有很多人碰到，意思是说字符编码不一样，不能进行比较，也就是说数据库内部的编码都不一样，有的数据是
gbk_chinese_ci,有的数据是gb2312_chinese_ci，因此解决此问题的核心就是将数据库所有的编码进行统一。
进入命令行模式，
如果MySQL数据库已经安装好，可以使用下列SQL命令查看MySQL当前的字符集设置：
mysql> SHOW VARIABLES LIKE 'character_set_%';
+--------------------------+----------------------------+
| Variable_name | Value |
+--------------------------+----------------------------+
| character_set_client | latin1 |
| character_set_connection | latin1 |
| character_set_database | latin1 |
| character_set_results | latin1 |
| character_set_server | latin1 |
| character_set_system | utf8 |
| character_sets_dir | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
7 rows in set (0.00 sec)
mysql> SHOW VARIABLES LIKE 'collation_%';
+----------------------+-------------------+
| Variable_name | Value |
+----------------------+-------------------+
| collation_connection | latin1_swedish_ci |
| collation_database | latin1_swedish_ci |
| collation_server | latin1_swedish_ci |
+----------------------+-------------------+
3 rows in set (0.00 sec)
依次执行：
[code]set character_set_client =gb2312;
set character_set_connection =gb2312;
set character_set_database =gb2312;
set character_set_results =gb2312;
set character_set_server =gb2312;
set character_set_system =gb2312; --此处utf-8也可以[/code]
然后执行：
[code]SET collation_server = gb2312_chinese_ci
SET collation_database = gb2312_chinese_ci
SET collation_connection =gb2312_chinese_ci
[/code]
执行完之后，请检查mysql下每个数据库，表，字段是否都是gb2312，不是则改过来，这样子就不会出现
Illegal mix of collations (gbk_chinese_ci,IMPLICIT) and (gb2312_chinese_ci,IMPLICIT) for operation '='这个错误了，网上有资料说要重装，其实根本就不必，改动其编码即可